freeipa/ipapython/certdb.py

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# Authors: Rob Crittenden <rcritten@redhat.com>
#
# Copyright (C) 2009 Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import os
import re
import tempfile
import shutil
import base64
from cryptography.hazmat.primitives import serialization
from nss import nss
from nss.error import NSPRError
from ipapython.dn import DN
from ipapython.ipa_log_manager import root_logger
from ipapython import ipautil
from ipalib import x509
try:
from ipaplatform.paths import paths # pylint: disable=import-error
except ImportError:
CERTUTIL = '/usr/bin/certutil'
PK12UTIL = '/usr/bin/pk12util'
OPENSSL = '/usr/bin/openssl'
else:
CERTUTIL = paths.CERTUTIL
PK12UTIL = paths.PK12UTIL
OPENSSL = paths.OPENSSL
CA_NICKNAME_FMT = "%s IPA CA"
def get_ca_nickname(realm, format=CA_NICKNAME_FMT):
return format % realm
def find_cert_from_txt(cert, start=0):
"""
Given a cert blob (str) which may or may not contian leading and
trailing text, pull out just the certificate part. This will return
the FIRST cert in a stream of data.
Returns a tuple (certificate, last position in cert)
"""
s = cert.find('-----BEGIN CERTIFICATE-----', start)
e = cert.find('-----END CERTIFICATE-----', s)
if e > 0:
e = e + 25
if s < 0 or e < 0:
raise RuntimeError("Unable to find certificate")
cert = cert[s:e]
return (cert, e)
class NSSDatabase(object):
"""A general-purpose wrapper around a NSS cert database
For permanent NSS databases, pass the cert DB directory to __init__
For temporary databases, do not pass nssdir, and call close() when done
to remove the DB. Alternatively, a NSSDatabase can be used as a
context manager that calls close() automatically.
"""
# Traditionally, we used CertDB for our NSS DB operations, but that class
# got too tied to IPA server details, killing reusability.
# BaseCertDB is a class that knows nothing about IPA.
# Generic NSS DB code should be moved here.
def __init__(self, nssdir=None):
if nssdir is None:
self.secdir = tempfile.mkdtemp()
self._is_temporary = True
else:
self.secdir = nssdir
self._is_temporary = False
def close(self):
if self._is_temporary:
shutil.rmtree(self.secdir)
def __enter__(self):
return self
def __exit__(self, type, value, tb):
self.close()
def run_certutil(self, args, stdin=None, **kwargs):
new_args = [CERTUTIL, "-d", self.secdir]
new_args = new_args + args
return ipautil.run(new_args, stdin, **kwargs)
def create_db(self, password_filename):
"""Create cert DB
:param password_filename: Name of file containing the database password
"""
self.run_certutil(["-N", "-f", password_filename])
def list_certs(self):
"""Return nicknames and cert flags for all certs in the database
:return: List of (name, trust_flags) tuples
"""
result = self.run_certutil(["-L"], capture_output=True)
certs = result.output.splitlines()
# FIXME, this relies on NSS never changing the formatting of certutil
certlist = []
for cert in certs:
match = re.match(r'^(.+?)\s+(\w*,\w*,\w*)\s*$', cert)
if match:
certlist.append(match.groups())
return tuple(certlist)
def find_server_certs(self):
"""Return nicknames and cert flags for server certs in the database
Server certs have an "u" character in the trust flags.
:return: List of (name, trust_flags) tuples
"""
server_certs = []
for name, flags in self.list_certs():
if 'u' in flags:
server_certs.append((name, flags))
return server_certs
def get_trust_chain(self, nickname):
"""Return names of certs in a given cert's trust chain
:param nickname: Name of the cert
:return: List of certificate names
"""
root_nicknames = []
result = self.run_certutil(["-O", "-n", nickname], capture_output=True)
chain = result.output.splitlines()
for c in chain:
m = re.match('\s*"(.*)" \[.*', c)
if m:
root_nicknames.append(m.groups()[0])
return root_nicknames
def import_pkcs12(self, pkcs12_filename, db_password_filename,
pkcs12_passwd=None):
args = [PK12UTIL, "-d", self.secdir,
"-i", pkcs12_filename,
"-k", db_password_filename, '-v']
pkcs12_password_file = None
if pkcs12_passwd is not None:
pkcs12_password_file = ipautil.write_tmp_file(pkcs12_passwd + '\n')
args = args + ["-w", pkcs12_password_file.name]
try:
ipautil.run(args)
except ipautil.CalledProcessError as e:
if e.returncode == 17:
raise RuntimeError("incorrect password for pkcs#12 file %s" %
pkcs12_filename)
elif e.returncode == 10:
raise RuntimeError("Failed to open %s" % pkcs12_filename)
else:
raise RuntimeError("unknown error import pkcs#12 file %s" %
pkcs12_filename)
finally:
if pkcs12_password_file is not None:
pkcs12_password_file.close()
def import_files(self, files, db_password_filename, import_keys=False,
key_password=None, key_nickname=None):
"""
Import certificates and a single private key from multiple files
The files may be in PEM and DER certificate, PKCS#7 certificate chain,
PKCS#8 and raw private key and PKCS#12 formats.
:param files: Names of files to import
:param db_password_filename: Name of file containing the database
password
:param import_keys: Whether to import private keys
:param key_password: Password to decrypt private keys
:param key_nickname: Nickname of the private key to import from PKCS#12
files
"""
key_file = None
extracted_key = None
extracted_certs = []
for filename in files:
try:
with open(filename, 'rb') as f:
data = f.read()
except IOError as e:
raise RuntimeError(
"Failed to open %s: %s" % (filename, e.strerror))
# Try to parse the file as PEM file
matches = list(re.finditer(
r'-----BEGIN (.+?)-----(.*?)-----END \1-----', data, re.DOTALL))
if matches:
loaded = False
for match in matches:
body = match.group()
label = match.group(1)
line = len(data[:match.start() + 1].splitlines())
if label in ('CERTIFICATE', 'X509 CERTIFICATE',
'X.509 CERTIFICATE'):
try:
x509.load_certificate(match.group(2))
except ValueError as e:
if label != 'CERTIFICATE':
root_logger.warning(
"Skipping certificate in %s at line %s: %s",
filename, line, e)
continue
else:
extracted_certs.append(body)
loaded = True
continue
if label in ('PKCS7', 'PKCS #7 SIGNED DATA', 'CERTIFICATE'):
try:
certs = x509.pkcs7_to_pems(body)
except ipautil.CalledProcessError as e:
if label == 'CERTIFICATE':
root_logger.warning(
"Skipping certificate in %s at line %s: %s",
filename, line, e)
else:
root_logger.warning(
"Skipping PKCS#7 in %s at line %s: %s",
filename, line, e)
continue
else:
extracted_certs.extend(certs)
loaded = True
continue
if label in ('PRIVATE KEY', 'ENCRYPTED PRIVATE KEY',
'RSA PRIVATE KEY', 'DSA PRIVATE KEY',
'EC PRIVATE KEY'):
if not import_keys:
continue
if key_file:
raise RuntimeError(
"Can't load private key from both %s and %s" %
(key_file, filename))
args = [
OPENSSL, 'pkcs8',
'-topk8',
'-passout', 'file:' + db_password_filename,
]
if ((label != 'PRIVATE KEY' and key_password) or
label == 'ENCRYPTED PRIVATE KEY'):
key_pwdfile = ipautil.write_tmp_file(key_password)
args += [
'-passin', 'file:' + key_pwdfile.name,
]
try:
result = ipautil.run(
args, stdin=body, capture_output=True)
except ipautil.CalledProcessError as e:
root_logger.warning(
"Skipping private key in %s at line %s: %s",
filename, line, e)
continue
else:
extracted_key = result.output
key_file = filename
loaded = True
continue
if loaded:
continue
raise RuntimeError("Failed to load %s" % filename)
# Try to load the file as DER certificate
try:
x509.load_certificate(data, x509.DER)
except ValueError:
pass
else:
data = x509.make_pem(base64.b64encode(data))
extracted_certs.append(data)
continue
# Try to import the file as PKCS#12 file
if import_keys:
try:
self.import_pkcs12(
filename, db_password_filename, key_password)
except RuntimeError:
pass
else:
if key_file:
raise RuntimeError(
"Can't load private key from both %s and %s" %
(key_file, filename))
key_file = filename
server_certs = self.find_server_certs()
if key_nickname:
for nickname, _trust_flags in server_certs:
if nickname == key_nickname:
break
else:
raise RuntimeError(
"Server certificate \"%s\" not found in %s" %
(key_nickname, filename))
else:
if len(server_certs) > 1:
raise RuntimeError(
"%s server certificates found in %s, "
"expecting only one" %
(len(server_certs), filename))
continue
raise RuntimeError("Failed to load %s" % filename)
if import_keys and not key_file:
raise RuntimeError(
"No server certificates found in %s" % (', '.join(files)))
for cert_pem in extracted_certs:
cert = x509.load_certificate(cert_pem)
nickname = str(DN(cert.subject))
data = cert.public_bytes(serialization.Encoding.DER)
self.add_cert(data, nickname, ',,')
if extracted_key:
in_file = ipautil.write_tmp_file(
'\n'.join(extracted_certs) + '\n' + extracted_key)
out_file = tempfile.NamedTemporaryFile()
out_password = ipautil.ipa_generate_password()
out_pwdfile = ipautil.write_tmp_file(out_password)
args = [
OPENSSL, 'pkcs12',
'-export',
'-in', in_file.name,
'-out', out_file.name,
'-passin', 'file:' + db_password_filename,
'-passout', 'file:' + out_pwdfile.name,
]
try:
ipautil.run(args)
except ipautil.CalledProcessError as e:
raise RuntimeError(
"No matching certificate found for private key from %s" %
key_file)
self.import_pkcs12(out_file.name, db_password_filename,
out_password)
def trust_root_cert(self, root_nickname, trust_flags=None):
if root_nickname[:7] == "Builtin":
root_logger.debug(
"No need to add trust for built-in root CAs, skipping %s" %
root_nickname)
else:
if trust_flags is None:
trust_flags = 'C,,'
try:
self.run_certutil(["-M", "-n", root_nickname,
"-t", trust_flags])
except ipautil.CalledProcessError:
raise RuntimeError(
"Setting trust on %s failed" % root_nickname)
def get_cert(self, nickname, pem=False):
args = ['-L', '-n', nickname, '-a']
try:
result = self.run_certutil(args, capture_output=True)
except ipautil.CalledProcessError:
raise RuntimeError("Failed to get %s" % nickname)
cert = result.output
if not pem:
cert, _start = find_cert_from_txt(cert, start=0)
cert = x509.strip_header(cert)
cert = base64.b64decode(cert)
return cert
def has_nickname(self, nickname):
try:
self.get_cert(nickname)
except RuntimeError:
# This might be error other than "nickname not found". Beware.
return False
else:
return True
def export_pem_cert(self, nickname, location):
"""Export the given cert to PEM file in the given location"""
cert = self.get_cert(nickname, pem=True)
with open(location, "w+") as fd:
fd.write(cert)
os.chmod(location, 0o444)
def import_pem_cert(self, nickname, flags, location):
"""Import a cert form the given PEM file.
The file must contain exactly one certificate.
"""
try:
with open(location) as fd:
certs = fd.read()
except IOError as e:
raise RuntimeError(
"Failed to open %s: %s" % (location, e.strerror)
)
cert, st = find_cert_from_txt(certs)
self.add_cert(cert, nickname, flags, pem=True)
try:
find_cert_from_txt(certs, st)
except RuntimeError:
pass
else:
raise ValueError('%s contains more than one certificate' %
location)
def add_cert(self, cert, nick, flags, pem=False):
args = ["-A", "-n", nick, "-t", flags]
if pem:
args.append("-a")
self.run_certutil(args, stdin=cert)
def delete_cert(self, nick):
self.run_certutil(["-D", "-n", nick])
def verify_server_cert_validity(self, nickname, hostname):
"""Verify a certificate is valid for a SSL server with given hostname
Raises a ValueError if the certificate is invalid.
"""
certdb = cert = None
if nss.nss_is_initialized():
nss.nss_shutdown()
nss.nss_init(self.secdir)
try:
certdb = nss.get_default_certdb()
cert = nss.find_cert_from_nickname(nickname)
intended_usage = nss.certificateUsageSSLServer
try:
approved_usage = cert.verify_now(certdb, True, intended_usage)
except NSPRError as e:
if e.errno != -8102:
raise ValueError(e.strerror)
approved_usage = 0
if not approved_usage & intended_usage:
raise ValueError('invalid for a SSL server')
if not cert.verify_hostname(hostname):
raise ValueError('invalid for server %s' % hostname)
finally:
del certdb, cert
nss.nss_shutdown()
return None
def verify_ca_cert_validity(self, nickname):
certdb = cert = None
if nss.nss_is_initialized():
nss.nss_shutdown()
nss.nss_init(self.secdir)
try:
certdb = nss.get_default_certdb()
cert = nss.find_cert_from_nickname(nickname)
if not cert.subject:
raise ValueError("has empty subject")
try:
bc = cert.get_extension(nss.SEC_OID_X509_BASIC_CONSTRAINTS)
except KeyError:
raise ValueError("missing basic constraints")
bc = nss.BasicConstraints(bc.value)
if not bc.is_ca:
raise ValueError("not a CA certificate")
intended_usage = nss.certificateUsageSSLCA
try:
approved_usage = cert.verify_now(certdb, True, intended_usage)
except NSPRError as e:
if e.errno != -8102: # SEC_ERROR_INADEQUATE_KEY_USAGE
raise ValueError(e.strerror)
approved_usage = 0
if approved_usage & intended_usage != intended_usage:
raise ValueError('invalid for a CA')
finally:
del certdb, cert
nss.nss_shutdown()